000
FXUS66 KLOX 160504
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
915 PM PDT MON SEP 15 2008

...UPDATED AVIATION DISCUSSION...

.SHORT TERM...
WITH A VERY SHALLOW AND STRONG INVERSION LESS THAN 600 FT DEEP
ACROSS THE AREA TODAY...AS WELL AS WEAK ONSHORE
GRADIENTS...TEMPERATURES SOARED ACROSS MUCH OF LOS ANGELES AND
VENTURA COUNTIES TODAY. ALTHOUGH TEMPS WERE QUITE WARM JUST ABOUT
EVERYWHERE AWAY FROM THE IMMEDIATE COAST...SANTA CLARITA AND THE SAN
FERNANDO VALLEYS SOARED TO BETWEEN 100 AND 105 DEGREES...WITH SANTA
CLARITA VALLEY REACHING
106 AT ONE LOCATION...WHILE OJAI CLIMBED TO 102 DEGREES. DOWNTOWN
LOS ANGELES WARMED UP TO 87 DEGREES. ABOVE THE INVERSION...MALIBU
HILLS REACHED 103 DEGREES. THE INTERIOR SECTIONS OF SLO/SBA COUNTIES
REACHED THE MID 90S TO NEAR 100.

CURRENTLY...LATEST SATELLITE IMAGERY INDICATED CLEAR SKIES ACROSS
ALL OF SRN CAL S OF POINT CONCEPTION...WHILE AREAS OF LOW CLOUDS
WILL BEGINNING TO FILL IN ACROSS CENTRAL COAST. SOME WEAK SUNDOWNER
WINDS HAVE DEVELOPED ACROSS PORTIONS OF THE SANTA BARBARA SOUTH
COAST AND FOOTHILLS WITH NORTH TO NORTHEAST GUSTS TO 35 MPH REPORTED
NEAR MONTECITO. SBA-SMX GRADS WERE -4.7MB. SURPRISED THAT WINDS HAVE
NOT BEEN STRONGER. BUT GRADS SHOULD RELAX AFTER MIDNIGHT.

HIGH PRESSURE ALOFT WILL BEGIN TO GET NUDGED EASTWARD WHILE A WEAK
NEGATIVE TILTED TROF PUSHES DOWN ACROSS THE CAL COAST ON TUE. TEMPS
WILL HAVE TO BE ADJUSTED LOWER ACROSS THE BOARD AS 950 MB
TEMPS...THICKNESS LVLS INDICATE SOME LOWERING DUE TO TROF. STILL
ANTICIPATE WARMER THAN NORMAL TEMPS ACROSS THE REGION...WITH SANTA
CLARITA LIKELY RISING TO OVER 100 DEGREES ONCE AGAIN TUESDAY...BUT
FEEL THAT ONSHORE PUSH WILL START A BIT EARLIER KEEPING AREAS LIKE
BURBANK NEAR 90 AND DOWNTOWN POSSIBLY A DEGREE OR TWO COOLER.
CURRENT FORECAST SHOWS INCREASE FOR TUESDAY AND WILL HAVE TO BE
ADJUSTED BY MIDNIGHT SHIFT.

THERE WILL BE SOME INCREASING MID LEVEL MOISTURE PUSHING ACROSS THE
INTERIOR SECTIONS OF SOUTHWEST CALIFORNIA TOMORROW. ALTHOUGH MANY
CONVECTIVE PARAMETERS WILL BE MARGINAL ACROSS THE MOUNTAINS OF LOS
ANGELES AND VENTURA COUNTY AS WELL AS THE ANTELOPE VALLEY...PWAT
VALUES WILL BE NEAR AN INCH AND K-INDEX VALUES CLIMB TO NEAR 35
ACROSS THE EASTERN LA COUNTY MTNS. WITH CONTINUED ABOVE NORMAL TEMPS
FOR THE MOUNTAINS AND ANTELOPE VALLEY...THE CONVECTIVE TEMPS COULD
BE REACHED...SO A SLIGHT CHANCE OF TSTMS LOOK GOOD AT THIS TIME.

...FROM PREVIOUS DISCUSSION...

FOR TUESDAY NIGHT AND WEDNESDAY...THE FLOW ALOFT WILL SHIFT TO THE
SOUTHWEST AND COMBINED WITH SLIGHT COOLING AND DECREASED INSTABILITY
ACROSS THE REGION...ONLY AFTERNOON CLOUDS WILL BE MENTIONED ACROSS
THE MOUNTAINS AND DESERTS FOR WEDNESDAY AFTERNOON. LATER SHIFTS WILL
NEED TO MONITOR THIS AS THERE MIGHT BE ENOUGH INSTABILITY FOR A
THUNDERSTORM OR TWO.

MEANWHILE...A SLIGHT INCREASE IN ONSHORE FLOW MAY BE ENOUGH TO
INSPIRE AN INCREASE IN MARINE CLOUD COVERAGE FOR COASTAL SECTIONS
SOUTH OF POINT CONCEPTION.

.LONG TERM...GFS AND EC ARE NOW IN AGREEMENT THROUGH MONDAY AS THEY
DEPICT A SMALL LOW MOVING INTO NORTHERN CALIFORNIA. LOOK FOR TROFING
PATTER THROUGH FRIDAY WHICH SHOULD GIVE US NIGHT AND MORNING CLOUDS
OVER THE COASTS AND MOST OF THE VLYS. THE WEEKEND MAY BRING A SLIGHT
WARMUP AS THE LOW PUSHES EAST OF THE REGION.

&&

.AVIATION...16/0500Z
S OF POINT CONCEPTION...MARINE LAYER NEAR 500 FT DEEP WITH LATEST
SATELLITE IMAGERY INDICATING CLEAR SKIES EVERYWHERE. CONFIDENCE IS
HIGH FOR VFR CONDS THROUGH TOMORROW. HOWEVER...NEED TO MENTION THAT
IF PATCHY STRATUS DEVELOPS NEAR COASTAL AREAS OF LA/VTU COUNTIES
OVERNIGHT...DENSE FOG COULD DEVELOP AFTER MIDNIGHT THROUGH EARLY
MORNING HOURS. LOCAL GUSTY NORTHERLY WINDS POSSIBLE NEAR KSBA
THROUGH MIDNIGHT.

N OF POINT CONCEPTION...MARINE LAYER HIGHER TO THE NORTH WITH IFR
CIGS LIKELY OVERNIGHT ACROSS THE CENTRAL COAST THROUGH 17-18Z...THEN
VFR CONDS SHOULD PERSIST. LOWER CONFIDENCE FOR IFR CIGS AT KPRB
BY 12Z TONIGHT WITH 15-16Z BURNOFF.


KLAX...HIGH CONFIDENCE FOR VFR CONDS THROUGH TUE AFTERNOON...EXCEPT
SOME MVFR HZ POSSIBLE BETWEEN 12-16Z.

KBUR...100 PERCENT CONFIDENCE FOR CAVU TAF THROUGH TUESDAY AFTERNOON.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
GALE WARNING (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/SWEET
AVIATION...KAPLAN

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